The present invention is directed to a drive system for a printing group. The printing group includes a forme cylinder, a second cylinder acting with the forme cylinder, and an inking system.
A printing group with a forme cylinder and a transfer cylinder driven as a pair is known from DE 44 30 693 A1. The forme cylinder is driven and transfers a driving force to the transfer cylinder via spur gears. In one embodiment, a journal of the forme cylinder, which is embodied as a rotor, can be axially displaced in the stator for adjusting the lateral register.
EP 0 644 048 B1 discloses cylinders driven in pairs. The possibility of coupling an assigned inking system to the drive combination of the pair is disclosed. In a schematic representation, the transfer cylinder is driven by the drive motor. A driving force is transferred from the transfer cylinder to the forme cylinder and from the forme cylinder to the inking system.
In DE 196 03 663 A1 a forme cylinder and a transfer cylinder, acting together with the forme cylinder, can be driven in parallel by a motor. The forme cylinder can be axially adjusted by the use of a gear, and can be displaced in the circumferential direction with respect to the transfer cylinder by the provision of helical gear teeth. An inking system that is assigned to the forme cylinder can be driven by use of a spur gear wheel arranged on the journal of the forme cylinder.
DE 20 14 070 A1 discloses a drive system of a rotary printing press in which cylinder pair of forme and transfer cylinders is driven from the forme cylinder. In order to provide an unequivocal driven connection in the friction drive of two transfer cylinders acting together, the two transfer cylinders are connected non-positively, but releasably, with each other.
The driving of a four-cylinder printing unit by the use of a drive system acting on the respective forme cylinder is known from DE 20 14 753 A1. At least one of the respective transfer cylinders that is driven by its respective forme cylinder can be charged with a braking force in order to prevent tooth flank shifts.
DE 25 53 768 B1 provides a selectively independent driving of a forme cylinder and its associated inking system. The drive combination of the forme cylinder and the transfer cylinder has a releasable coupling. In one possible embodiment, a transfer cylinder and an inking system of a printing group can be driven by a drive motor that is acting on the forme cylinder.
DE 40 01 626 A1 discloses a drive train in which the driving force is transferred in a parallel manner from a counter-pressure cylinder to an inking system and to a transfer cylinder, and from there to a forme cylinder. In this way interferences are re-transferred to a lesser degree from the inking system the forme cylinder.
The object of the present invention is directed to providing a drive system for a printing group.
In accordance with the present invention, this object is attained by the provision of a printing group having a forme cylinder, a second cylinder acting with the forme cylinder and an inking system assigned to the forme cylinder. A drive system acts on the forme cylinder which drives the second cylinder through a drive connection. The inking system is driven by the second cylinder by a drive connection.
The advantages to be gained by the use of the present invention consist, in particular, in that, because of the drive system being at the forme cylinder, no movement of the drive motor need to occur when the transfer cylinder is placed into the print-on and print-off positions, such as would be the case, for example, in connection with a drive taken directly from the transfer cylinder. Also, a compromise, which would be necessary, based on such pivot movements of the transfer cylinder with regard to the position of the drive motor and the meshing of the gear wheels when the drive motor is arranged on the transfer cylinder, can be omitted when the forme cylinder is driven. Otherwise such pivot moments could lead to gear tooth breaks or to a reduction of the printing quality because of play in the drive system caused by such movements.
The drive system of the printing group in accordance with the present invention is independent of the drive system of a further cylinder or of a further printing group which, together with the printing group, constitutes a printing position. The drive system preferably does not have any mechanical, and in particular does not have any positive drive connection with the latter.
If only the inking system and the transfer cylinder are configured for making and releasing contact, a rigid connection of the drive motor with a frame can be provided.
A pinion gear of the drive motor, which is provided with straight teeth, can transfer power directly to a straight-toothed pinion gear wheel located at the journal of the forme cylinder, provided that the straight-toothed gear embodiment assures the required strength values, for example extent of coverage and breaking resistance.
In another embodiment of the present invention, the drive motor can be positioned directly axially aligned in relation to the forme cylinder. To make possible an axial movement of the forme cylinder, which is necessary for the purpose of adjusting the lateral register, a coupling, which is flexible or shiftable in the axial direction, can be arranged between the forme cylinder journal and the drive motor. The embodiment of the present invention with the drive motor having a planetary gear arranged between the rotor of the drive motor and the journal of the cylinder is advantageous in respect to providing desirable ranges of the numbers of revolutions, in particular in the start-up phase of the printing group.
In those cases where strength requires helical gear teeth for force transfer, a drive arrangement is advantageous in which the pinion gear of the drive motor does not transfer power directly to the spur gear wheel of the forme cylinder. In such a case, a displacement of the circumferential register would take place simultaneously with an axial movement of the forme cylinder, unless additional measures have been taken. These measures would be, for example, a simultaneous correction through the provision of a control device. Such a correction requires an outlay for such regulation, or requires a permissible relative movement of the journal with respect to the spur wheel of the forme cylinder which relative movement, however, requires guide devices that cannot, or only with a large outlay, be produced free of play in the circumferential direction. A coupling, which is flexible in the axial direction, could again be employed, in an advantageous manner, for the axial mobility of the forme cylinder.
It is advantageous, in connection with the above-discussed preferred embodiments of the drive system of the forme cylinder in accordance with the present invention, if an inking system that is assigned to the forme cylinder and, if provided, a dampening system, are also driven by the same drive motor. This saves expense and assures synchronization, provided that the correct transmission ratios are employed.
An unequivocal and certain flow or transfer of moment or drive torque from the drive motor to the various units to be driven is particularly advantageous for the exact roll-off of the cylinders and rollers during production. In an advantageous embodiment, this is achieved because driving takes place from the forme cylinder to the transfer cylinder, and from the transfer cylinder to the inking system serially. In this connection, an embodiment is particularly economical in which driving takes place from the transfer cylinder to the inking system through a gear wheel, which gear wheel is rotatably seated on the journal of the forme cylinder.
A coupling between the drive motor and the forme cylinder, which coupling is flexible in the axial direction is embodied, in an advantageous manner, as a shaft coupling, which is flexible, or yielding, in the axial direction. Such a shaft coupling can be, for example an expansion coupling or a compensation coupling. The employment of a non-shiftable, positive shaft coupling which, in contrast to other positive couplings, is almost free of play in the circumferential direction, without requiring a large production outlay, and which simultaneously allows an axial length change of the coupling, such as an axial movement of the forme cylinder, is particularly advantageous. The coupling is embodied to be positive in the axial direction, but is flexible or yielding in length, for example by the provision of an elastic and reversible deformation.
The steps for an unequivocal and certain moment or torque flow direction and, if a coupling is required, for the embodiment of the latter as a torsion-proof, but longitudinally adjustable coupling, are used for minimizing the play in the drive system, and for an improvement of the print quality because of this.